Snow and ice can create hazardous conditions on roads, sidewalks, parking lots, wherever there is either vehicular traffic or pedestrian traffic. It is most desirable that snow and ice control compositions meet certain criteria among which are: (1) efficiency of snow and ice control; (2) it is desirable that the snow and ice control composition is non-corrosive to metals; (3) the material should not cause any deleterious effects on road surfaces; (4) it is relatively innocuous and does no harm to the environment; (5) that it does no damage to plant, animal, or human life.
Prior art is replete with the use of sand or cinders to obtain traction, that is, to provide a gritty surface thus allowing vehicles and pedestrians to obtain traction, additionally, sodium chloride or calcium chloride pellets may be employed to melt the ice and snow; combinations of the two have also be used. In recent years attempts have been made to provide snow and ice control compositions which contain corrosion inhibiters to help prevent corrosion of metals. U.S. Pat. No. 3,630,913 teaches the use of a fluid deicer composition containing urea, ammonium nitrate, ethylene glycol, water and chromate salts to provide non-corrosiveness of both ferrous and non-ferrous materials. The use of heavy metal salts to provide non-corrosive properties is counterproductive since these materials are toxic both to humans and in large quantities to animal and plant life. Another snow and ice control composition is taught in U.S. Pat. No. 3,928,221 which contains a mixture of urea, ethylene glycol, and methanol. A more recent U.S. Pat. No. 4,108,669 teaches that a satisfactory snow and ice control composition can be prepared by the addition of 1-20% by weight of ammonium nitrate by applying an aqueous solution of ammonium nitrate onto calcined montmorillonite.
Older patent references include U.S. Pat. No. 2,308,289 which teaches the use of sand containing sodium chloride. Similarily U.S. Pat. No. 2,410,910 teaches the same use of sodium chloride being contained within cinder particles. Several foreign patents, specifically Ger. Pat. No. 1,459,684 teaches the use of treating pumice, a natural porous volcanic rock treated with urea. Other combinations are found in subsequent foreign patents. For example Ger. Pat. No. 2,148,505 teaches the use of glycol or some other similar polyhydroxy compounds adsorbed onto mineral wool, sand or gravel while Ger. Pat. No. 2,517,618 teaches the addition of adding carbon soot to salt.
Despite this voluminous number of patent citations the fact remains that all of the prior art have very serious limitations. These limitations include, poor leachability of a solute from a particle; poor crush resistant properties, so as to minimize traction; environmentally unsound snow and ice compositions causing serious damage to roads and causing irreversible environmental damage; or being inneffective in lowering the melting point to cause the snow and ice to change from a solid to a liquid state.